Fat transplantation is a surgical operation performed to fill a space where soft tissues of a patient have ever occupied, and particularly, is performed for cosmetic purposes such as removing wrinkles, dimples, or the like. The worst disadvantage of the fat transplantation is that the transplanted fat is suctioned into the patient and the volume thereof is reduced.
If the suctioning force applied to fat during extraction is excessively high, approximately 80% to 90% of the fat cells do not survive transplantation, necessitating that the surgical operation be repeated. Moreover, when the fat is suctioned into the patient, since the dead tissue serves as a source of infection or decomposed material may be toxic, serious scarring may occur or normal skin tissue around the skin into which fat is transplanted may be damaged.
Autologous fat transplantation requires that red blood cells and free oil liberated from ruptured fat cells be removed from the suctioned fat. When a red blood cell is escaped from blood vessel, the red blood cell is decomposed and produces thromboxane A2. The thromboxane A2 serves as an ionized free radical to demolish normal tissues, thereby demolishing fat tissues. Thus, engraftment of the transplanted fat is remarkably reduced.
The free oil is decomposed upon separation from an adipose cell and is ionized into a free fatty acid. The free fatty acid is a free radical, thereby destroying normal tissues and adipose cells. Thus, the free fatty acid reduces the engraftment of the transplanted fat and induces cell death, which in turn leads to secondary inflammation or serves as a culture medium of bacteria. Moreover, the free oil, remaining between the adipose cell wall and the adipose cell, serves as a capsule and disturbs oxygen supply essential to the survival of the transplanted adipose tissues. Accordingly, free oil is one of the principle reasons for death of transplanted adipose tissue.
For this reason, although the free oil must be removed prior to the fat transplantation, some of the free oil is transplanted and causes trouble. Particularly, when a great deal of fat is transplanted, the free oil accumulates below the transplant area, thereby causing inflammation or tissue death, or enlarging granulomata that is touched like a tumor.
According to the conventional art, in order to remove red blood cells and the free oil, the following methods are used. The first is the most primitive and involves storing suctioned fat in a funnel-shaped vessel until red blood cells and the free oil are separated from the sucked fat. As time passes, blood, bodily fluids, and pure fat layers are gradually formed in turn from the bottom of the sucked fat, and impurities such as the blood and bodily fluids are removed until the pure fat is tinged with light yellow. However, it is difficult to separate the free oil via the above-mentioned method, and it takes a long period of time.
The second method involves wrapping the sucked fat with a cloth and squeezing the cloth by hand to separated impurities from the sucked fat. When squeezing the wrapped fat, the sucked fat is pressed and the free oil can be separated from the sucked fat, and the cloth functions as a filter for filtering various impurities. However, this method is disadvantageous in that it takes a great deal of time to separate free oil, the separation procedure is complicated, and, above all, there is a risk that the separated free oil may be infected due to the contact with air.
A third method involves suctioning fat into a syringe type vessel and separating the free oil via density gradient centrifugation. After the density gradient centrifugation of the sucked fat, red blood layer is positioned at the lowest layer and is clearly distinguished from other components. The free oil forms the supernatant such that the free oil is positioned above the adipose cell layer and forms an emulsion with the adipose cell layer. In order to remove the red blood cells, since pressure must be applied from the upper side of the syringe type vessel, the upper free oil may be mixed with the pure fat again. Thus, the free oil must be separated in the first place such that a syringe needle is inserted into the highest layer to extract only the free oil, or a piston or cap is removed from the syringe vessel and the syringe type vessel is turned upside down such that the free oil is immediately discharged from the syringe type vessel. Next, when only the pure fat is positioned on the highest layer, pressure is applied to the upper portion of the syringe type vessel to press the fat and to discharge the red blood. However, the former step needs a lot of time and manpower, and the latter has risks such as inflammation due to contact with air and loss of the pure fat.
Therefore, since, in the above-mentioned methods, it is difficult to simultaneously separate the red blood having the highest specific gravity and the free oil having the lowest specific gravity from the sucked fat, the procedures are complicated and inflammation occurs upon transplantation. Particularly, since the free oil is not effectively separated, the desired volume substitution cannot be effected.
The fourth method uses a piston having a syringe type vessel without a shaft. The piston, invented by this inventor, has a piston head of a syringe used in fat transplantation having a filter for passing air and water and for filtering fat (Korea Registered Utility Model No. 0327374). During the suction of fat by external pneumatic pressure, air and water are removed from the sucked fat, and water and free oil contained in the sucked fat are filtered from the sucked fat by pressing the sucked fat. The above syringe piston uses the conventional syringe type vessel and the external pneumatic pressure to remarkably enhance fat suction efficiency. According to the syringe piston, fat can be pressed without the density gradient centrifugation, the fat is hardly infected when contacting external air during the treatment of the fat, and the red blood and the free oil can be effectively removed in comparison with the above-mentioned methods. However, some of free oil or red blood cells contained in the sucked fat may remain in the syringe used in the fat transplantation during the pressing. Moreover, if the pressure or the suction force is not properly and accurately controlled, adipose cells may be discharged from the syringe used in the fat transplantation. Additionally, since the syringe used in the fat transplantation has a structure wherein bodily fluids such as free oil is passed through the filter by external pneumatic pressure, the filter is formed with fine holes of about 5 μm to 50 μm so that the filter may be easily clogged. Moreover, when the filter is very fine and accurately formed, the adipose cells can be prevented from being discharged from the syringe used in the fat transplantation.